(i) Methods are being developed for the detection of very low concentrations of flourescently labeled proteins in the presence of very high concentrations of unlabeled proteins and polymers. These techniques will be used to investigate non-specific protein/protein and protein/polymer interactions in solution. (ii) Antibody presentation is a key step in the initiation of the adaptive immune response, depending on the expression of costimulatory molecules. Immune-enhancing oligodeoxynucleotides (ODNs)increase the expression of these molecules. CD measurements were used to show that several of these regulatory ODNs contain guanine(G)-tetrad structures. Heat treatment of these ODNs which diminishes their regulatory properties also destroyed the G-tetrads. (iii) Optical studies on the structures of amyloid peptides and proteins are continuing.We are particularly interested in origin of the very intense CD spectrum which has been associated with the cross-beta structure of amyloid fibrils.